Effect of hot deformation parameters on the dynamic recrystallization mechanism of TAS31608/LH austenitic stainless steels

Plates for liquid hydrogen storage tanks are used in ultra-low temperature and harsh corrosive environments, which require uniform microstructure. The microstructure evolution of continuous casting billets is directly impacted by high-temperature rolling. Herein, the hot deformation behavior of TAS31608/LH austenitic stainless steel is studied by hot compression tests in the temperature range of 1000–1200 °C and the strain rate range of 0.01 − 10 s⁻¹. The hot compression test is carried out by the Gleeble thermal mechanical simulator, and the microstructure is characterized by electron backscatter diffraction (EBSD). The effect of the temperature and strain rate on the dynamic recrystallization (DRX) mechanism is demonstrated. The results suggest that the continuous dynamic recrystallization (CDRX) is the auxiliary DRX mechanism, and the discontinuous dynamic recrystallization (DDRX) is the principal DRX mechanism during hot deformation. When the temperature and strain rate increase, the low-angle grain boundary (LAGB) shifts to the high-angle grain boundary (HAGB), and the proportion of twins and DRX gradually increased. Additionally, residual δ-ferrite promotes the DDRX behavior. However, δ-ferrite hinder the growth of recrystallized grains, which lead to the appearance of the mixed crystals. Due to the promotion under high temperatures and strain rates for DRX, the 1200 °C–10 s⁻¹ is the optimal hot deformation parameter of the TAS31608/LH.